Investigation of humidity-driven swelling- shrinking behavior of filaments in material extrusion of medical-grade biodegradable hydrogel

Abstract

Material extrusion using medical-grade biodegradable hydrogel demonstrates significant potential for manufacturing biocompatible scaffolds in regenerative medicine. However, unpredictable geometric variations in the fabricated models, such as swelling or shrinking, impede the development of complex three-dimensional (3D) hydrogel architectures for in vitro-functionalized tissues and organs. A primary cause of structural deformation, such as wrinkling or even collapse, is improper humidity control during the 3D printing process. Therefore, there is a need to investigate the swelling-shrinking behavior of hydrogels under varying ambient humidity and to determine optimal humidity levels for the printing process. This study established a thermal-humidity-multiphase flow coupling field simulation model to numerically investigate the humidity-driven swelling-shrinking behavior of hydrogel filaments. The optimal 3D printing humidity levels were determined for hydrogel filaments with diameters of 0.2, 0.3, and 0.4 mm, which were found to be 90, 80, and 60%, respectively. Using these humidity settings, several structures were fabricated, demonstrating moderated moisture loss of 3D architecture. Notably, a human ear model was successfully printed, achieving an effective size of 20 mm (length) × 10 mm (width) × 10 mm (height). Our research can benefit the future development in tissue engineering and regenerative medicine.

Keywords

3D printing / Coupling field simulation / Humidity control / Medical hydrogel

Funding

The authors deeply acknowledge the financial support from the Key Research and Development Plan Project of Heilongjiang Province (grant no. 2022ZX02C22); the Science and Technology Innovation Talent Project on Manufacturing Industry of Harbin (grant no. 2023HBRCGD011, 2022CXRCGD029); the Interdisciplinary Research Foundation of HIT (grant no. IR2021223); and the Natural Science Foundation of Chongqing (grant no. CSTB2023NSCQ-MSX0822).

Conflict of interest

Dr. Swee Leong Sing serves as the Editorial Board Member of the journal, but did not in any way involve in the editorial and peer-review process conducted for this paper, directly or indirectly. Other authors declare they have no competing interests.